After completing a flightplan in the FMC I inadvertently swept my hand across the left-hand end of my keyboard. I witnessed the flightplan swivel clockwise through 17 degrees on the HSI which had the effect of causing my first waypoint heading to end up at 330 degrees instead of 313.I afterwards noticed that my already saved flightplans for the 747-400X were affected in exactly the same way.I removed and re-downloaded both aircraft from the PMDG downloads site but the disorientation remains.None of my other aircraft addons are affected.Clearly some key or keys on the keyboard have the effect of changing the flightplan orientation, but I have no idea which.Has anybody had a similar experience, and do they know how to correct it?Colin Turner

Maybe you were in MAG heading and you switched to the TRUE heading?